The present invention relates to an adjusting arrangement for a seat, particularly a power vehicle seat, for inclination adjustment of a backrest.
Arrangements of the above mentioned general type are known in the art. In a known arrangement, the backrest is connected with a seat part by hinges provided at both sides, and each hinge has a hinge part associated with the backrest and a hinge part associated with the seat part and connected with one another via a pivot axle. The arrangement is also provided with displacing and fixing means which determine the position of the hinge levers relative to one another and is formed as a wobble drive including an eccentric associated with the pivot axle and composed of two wedge segments which are held by a pressure accumulator in a force-transmitting abutment on the pivot axle. Such an arrangement is disclosed, for example, in the German Offenlegungsschrift No. 3,013,304. This arrangement is formed of two hinges each arranged at each seat longitudinal side between the seat part and the backrest. Each hinge has a pivot axle by which both hinge levers of each hinge are connected with one another. One hinge lever, for example the hinge lever connected with the backrest, is supported on a centric portion of the pivot axle, whereas the other hinge lever, for example the hinge lever connected with the seat part, is supported on an eccentric. The outer toothing of the eccentric engages in the inner toothing of the first mentioned hinge part and forms with the same a so-called wobble drive. The eccentric is composed of a cam disk which is connected for joint rotation with the pivot axle and has two cam projections offset from one another, and also includes two wedge segments arranged between the cam projections and spread from one another by a pressure accumulator. The wedge segments are pressed on the cam disk, on the one hand, and, on the other hand, pressed on the inner opening of the hinge part surrounding the eccentric. Because of the wedge segments which are spreadable from one another, the toothing, on the one hand, and the bearing points, on the other hand, are prestressed in a play-free manner relative to one another. When the rotation of the pivot axle is actuated via a cam projection of the respective neighboring wedge segment in releasing direction, a play which facilitates the displacing movement is generated. Both pivot axles of the hinges arranged at both seat longitudinal sides are connected with one another in a known manner by transmission rods which engage in non-round openings of each pivot axle. Because of the play at the connecting points between the transmission rods and the pivot axles of each hinge in connection with the elasticity of the transmission rod itself and also because not exact coincidence of the eccentric's highest points of both hinges, an intermittent movement takes place during adjustment of the backrest inclination, particular1y in the hinge in which the adjusting movement is transmitted through the transmission rod. This intermittent movement is identified by experts as judder movement. Such a judder movement causes, particularly in addition to a uneven movement course, also noise during the adjusting movement. Special difficulties take place in such backrests in which the frame, because its construction is relatively rigid.